Chromium-free air-hardening alloy steels and articles of manufacture produced therefrom



rem Jul, a1, 1045 Um'rsn as 6. Dev Ladhm NDra J s'eem Menalida, N. Y, stclil m mum aeeqeratlsne! 10 Ollhna. (Cl. 75-125) present invention relates to air-hardening whichareuseiulbothinthecastand wrought condition for the production 01' dies and-structural members and which are characterisedbytheiactthattheycontaina small amount oi beryllium butno chromium.

Conventional air-hardening steels containing chromium are expensive to harden and are deiie nitely restricted as to the decree oi hardness which can 'be imparted thereto. Hardening is carried out from temperatures in the range oi 1800-1900 I". and considerable dimculty is encountered in obtaining hardness values as high as800Brinell. Caremmtalsobetakentocorrelate properly the carbon, and chromium contents in order to minimise or avoid undue brittleness. loss oi toughness, decrease inhardenahility and Air-hardening steels er the Mushet ty e contain a substantial amount oi-tungsten and sometimesasmall amountotchromiumandarelikewise expensive and rather diincult to produce.-

tially the iollowing composition: carbon, .05- 2.50% silicon, 504.50%; manganese. 354.25%: molybdenum. 254.50%; copper, 354.00%: and beryllium. Jill-.8096, the balance being substantially all iron except in the usual impurities in normal amounts.

.A still further object of our invention is to produce beryllium-containing alloy steels as hereinatter defined in which the formation of graphite incastlngsandiorgingscanbecontrolled.

A stilli'urther object or our invention is to provide air-hardening steels containing beryllium andcopperandwhichcanbecasttoshapeand .size with good fluidity.

Other and further objects and advantages will beunderstoodbythoseskilledinthisartorwill be apparent or pointed out hereinafter. I

Our invention is predicated upon the discovery that alloy steels with unusually good hardening I properties can be produced without chromium or whilebotht'ypeeoi'air-hardeninzsteelsare,

commercially employed they are far from ideal, withtheresultthattheindustryisstillseeking improved compositions which are more versatile in their applications.

. One of the objects or our present invention is to produce alloy steels which are air-hardening and yet which contain no chromium or tungsten,

.which are easier and less expensive to harden and which can readily behardenedto high hardness values from relatively low temperatures.

Another obiect or our invention is to produce a beryllium-containing chromium-tree air-hardeningalloysteelwhichhasnewanduseiul properties and characteristics and which in particular iscapable oireadily acquiringahardness valueo1atleastBO0Brinelland60ConeRock-- f well by air cooling atter heat treating to the abnormally low temperatures of 1450-1550 1''.

- a further obiect o! ourinventionfresides-in producing new and useful alloy steels substantungsten by incorporating beryllium therein especially in conjunction with copper.

we have discovered that even extremely small amounts of beryllium in the presence or copper and in combination with the other elements specified. not onlyrenders such steels air-hardening but they can be hardened to high values of hardness above 600 Brinell and 80 Cone Rockwell. Even a few. hundredths of a percent of beryllium endow these alloy-steels with the de-' sired properties and in addition make possible a substantial decrease in the cost or hardening because hardening can'be eiiected i'rom abnormally 'low temperatures 01' about 1450-1550' 1". in direct centrist with prior steels which must-be hardened from a temp rature 01' 1800-1000 '1". The

elimination 'o! chromium has advantages which will be appreciated by the metallurgist and in addition steels beryllium and copper are far superior to chromium and tungsten steels i'ormanypurposea.

Ournewalloys teelsconsistoLinadditionto ironandtheusuaiimpuritiuinnormalamounts.

about Jib-2.50% carbon, about 504.50%. silicon, about HIS-8.25% manganese, about 354.50% molybdenum, about .85-2.00% copper. and about 33-30% beryllium.

Illustrative examples of compositions responding to our present invention and a few other compositions included for comparative purposesare set forth in Table I, which follows:

sameamountofcopperasT-zm. Ithfurther noteworthy that the beryllium content or composition T-rlbisonlymqe andthattheamounts oftheother elementsareccmparable. Thesisniiicance of this willbe more fully appreciated from compositionT-Ml which in a cast piece havingacrosssectionaboutthreetimesasgreat as composition T415 has practically undimin- Tdblll' Asaanealed Asicrgsd a 0 s1 m1 Mo On Be use I. we r.

No. 1 Biases- Al 31 no rue n a 11: no 111- ao T-nn-.- 1.21 1.14 no .so 1.so .04 an as r 1"sq en es :1". an as 11-11.. m 1 -201..- 1.3a 1.1: 1.00 .ss 1.so .01 so s1-r 2%" 001 u nil-11.. xv. em as eso T-mo--- 1.20 1.111 1.01 us 211 as r 1' on m 16''. an a loft... 1.1m 1 -211--- 1.25 1.011 2.10 1.1111 ass as r 1 n.- m 01 Bard" n". as so EenL. an 'r-215 1.11s 1.01 1.00 1.1a 1.2: .01 m as r 1 'an.. s11 01. n s: as ea n an 'r-21s 1.11 .112 1.51 1.90 1.20 m as r 27.... em a I 110 a: 001 so 41o T2l9 1.12 .an 1.14 1.11s ass a r u as 41 .3: :11 as .-.do... son 1 -241..- 1.11 1.11s 2.92 1.111 1.111 .01 m n r s14 as u 11-11.. ,100

1.30 1.11 ass ans 1.1a "4'2"... as: on Har Nona-(o) F"=eoft. (b) Magnetbdm gepoinMhe magnetisshangesnotedmooelhlgnomtlnhardmingtempuatnnmdisated.

This table illustrates the hardness values so ished hardness values. Composition 50544: is

dimensions of the piece in question as will be more fully appreciated from our co-pending application, Serial Number 452,637, filed July 28," 1942. In that application we have pointed out that, other things being equal, hardness values are inversely proportional to the mass of metal involved, particularly the cross-sectional area of the piece undergoing hardening. Therefore, merely because a given procedure will produce desirable hardening characteristics in a piece of one size does not signify thatthe same'hardness characteristics will result when all the conditions are the same except that the size of the treated piece is larger. These statements apply particularly to steel T-214 which in a piece 1%" round (corresponding to a cross-sectional area of 1.78 Sq. in.) can be hardened to 827 Brinell and 81 Cone Rockwell but in the cast state with dimensions of 2" x 2%" (corresponding to a cross-sectional area of 5 sq. in.) hardens to a considerably less extent, viz... only to 578 Brinell and 59 Cone Rockwell. In still larger since it doesnot even approach the required hardness of 600 Brlnell and 60 Gone Rockwell either in .the as cast or the as rolled condition.

contrasted with this, steel T-2l8 (Table I) which contains 1.3% of copper but no beryllium shows good hardness characteristics as forged to a piece 2" x 2%" (which corresponds to a crosssectional area of 5 sq. in.) and still shows nearly thesamehardnesscharacteristicsinacasting,

than three times as great as composition T-flls 'andmorethannine (9) timesasgreatascclmposition T415 shows the highest Brinell hardness value ,and a Cone Rockwell'hardness equal to the best obtained for any composition and size,even the l" forged section of composition $403 which has exceilenthardness characterics. 1

As will be apparent from the ranges set forth above, the carbon content of our new compositions may range from a minimum of about 05% to a maximum of about 2.5% and our compositions present no difficulty in forging or rolling throughoutthis carbon range except that for values of 1.50-2.25% of carbon forging and rolling are somewhat less readily eiifectecl. The various ranges of compositions do, however, have marked diilerences with reference to size limitations of hardening and when the silicon content is lowered below .'I5%-hardening is materially less effective than in those compositions containing more than 115% of silicon. These facts make it necessary to exercise considerable caution in evaluating the results obtained because steels containing an amount of silicon in the lower portion of therauge specified can still be hardened from a low temperature. The higher silicon steels in conjunction with the higher m:

contents of the order- ,of 1-159: contain morethan steels carbon within the range of approximately Lilo-1.50%. This is due to the fact that the hardness values of the former are somewhat lower than those of the latter after annealing.

The occurrence of graphite in the manufacture of air-hardening steels containing the above indicated amounts of silicon from a cast ingot to a finished forged or rolled bar, or during the manufacture of any particular casting to the n finished forging, is primarily a function ofthe mass of metal involved in the particular operation. Our investigations showed the presence carbon. Reference is had to Table 11: which of free graphite in small masses of metal and follows:

Table II ghrllwl' i 0 s1 Mn Mo Cu Ni n0 File r. um treatment Brlnell Bile Bl- B0 1.25 2.00 1.50 1.25 1.50 .05 255 Bolt.-- 1.39 2.00 1.70 l.% 1.56 1,450/1 ill-ll! 56 555 1"!3" 1.25 1.50 1.50 1.75 1.25 04 M2 27 Soft... 1,450/1lmnii' 64 082 94x3" 1.39 1.48 1.64 1.90 1.2! 1,450/2hr.nir 53 653 2' x134" 1.25 2.00 1.25 1.25 1.50 0.75 05 ...a. 1.35 1.84 1.38 1.26 1.54 .87 223 19 Soft--. 1,450/2111'411' 00 601 2"x1l6" 1.10 2.20 3.25 .80 1.50 .05 1.18 1.95 3.44 1.05 1.50 353 39 Bolt--. 1,4m/2hl'.ail' 58 555 2sq. x2"

1.45% and beryllium, .09%, it 'being understood that the balance of the steel was iron and the usual impurities in normal amounts. This 600 pound heat was cast into an ingot 8 inches square. Three portions of that ingot were forgedtobillets which were respectively 6 inches square, 4 inches 40 square and 2 inches square, and in producing these billets the identical heat treatment was given to the three diiferent ingot portions and after forging the three billets wer given identical annealing operations. Examination of these" billets showed the presence of free graphite in the 2 inch square billet but the 4 inch square Such steels can be cast and forged and subsequently hardened to the hardness of tool steel (substantially to 600 Brinell or more) and they may contain graphite. The presence of graphite can be insured, as will be appreciated from what has preceded, either by making the initial casting of comparatively small size or section or by forging an initially large casting or a portion of an initially large casting .into such size that graphite is formed easily during the forging and subsequent annealing operations. Thus, in accordance with our invention and in connection with compositions having l-l.5% of carbon, as exemplified by Table II, the production of graphite is easily controlled and those forgeable graphits-containing steels may be utilized in an unhardened or semi-hardened state if preferred or desired.

Table III, which follows, illustrates compositions with a carbon content near the upper porand 6 inch square billets showed practically no tion of th indi ated range:

Table In M it 011 0 H n t c c 81111 e 38 [9B- 0118 O Si Mn M0 B9 chillcast meal; size Rockwell File Rockwell r-sa 1.10 1.10 1.38 .ss .10 sown"-.. 1,400F.alr m- '00 Hard. T-54 1.87 1.13 1.04 .ss .10 21.50-- 00-. .00-- 01 Do. T-55 2.00 1.00 1.50 1.oo 0.15 .10 31c. 00-- 110-- 04 Do.

free graphite. The cycle of heating preliminary so The designated steels are particularly useful to the forging and annealing after forging were of such' extended duration that the absence, or substantial absence of graphite could not possibly be due to inadequate heating. It is thus clear that the size of the initial casting and the size of the forging produced therefrom has a controlling effect upon the production of free graphite in the low temperature air-hardening steels responding to our present invention. For

for castings employing relatively large amount of carbon such as cast cylinders and the like, but these high carbon steels have only a relatively limited application to tool steel purposes. These steels still harden well in small sizes from temperatures as low as 1400-1500 F. and at slightly higher temperatures a somewhat greater degree of hardness can be secured. The steels of Table .111, however, exemplify a distinct class of steels which can be easily machined in the cast and annealed' condition and in which the order of machinability is that of a good grade of gray cast iron.

' Reference is next had to Table IV, which folinvention thus includes the production of steels [7g lows:

Table!!! Annealed H 1100' r. mo" r. was r. 0 Mn s1 Cu Mo Be Size cool new Obnair obnalr .ooor Brinell Brinell Brinell s02 1.03 2.06 1 51 1.90 2.00 .00 s"rd.xs"long. 302 we can N3 1.48 1.36 1.88 I. 2.62 .M -d 302 678 601 204 -.1.7s 20s 1.41 1.28 an .00 .....do ass m 578 20s 1.4; 208 1.4a as: do m 352 an In this table we show the analyses and hardening characteristics of four different heats of steel cast into rounds 5 inches in diameter and 5 inches long. From this tableit can be observed that heat #205 containing neither copper nor beryllium hardens to an extent only little more than half oi the hardness value of heats #202, #203 and #204, even though the balance of the compositions was substantially identical. Thus, compositions such as those set forth and containing both copper and beryllium can be easily hardened to high hardness values of substantially 600 Brinell or more in direct contrast to a similar composition but without copper and beryllium.

In our co-pending applications, Serial No. 452,636, filed July 28, 1942, and Serial No. 452,- 639, filed on July 28, 1942, we have described chromium containing air hardening steels which can be cast to ultimate shape and dimensions with good fluidity. The same thing is true of our present compositions even though they contain no chromium and this, it will be appreciated, is a worthwhile advantage. While we have shown that the higher carbon steels can be air-hardened from unusually low temperatures around 1450 F., steels with lower carbon quenched in oil or in water to produce excellent physical strength and elongation. A typical set of such cast steels and the physical properties thereof are set forth in Table V. These steels can be quenched, irrespective of whether or not they have had a preliminary subcritical anneal, to

produce cast parts having adequate strength coupled with high ductility:

Having described our invention, what we claim as new and desire to secure as Letters Patent are:

1. A tool, die and structural steel consistin of the following elements in substantially the following amounts: .05-2.50% of carbon, .50- 2.50% of silicon, 354.25% of manganese, .25- 2.50% of molybdenum, .35-2.00% of copper and .03-.30% of beryllium, the balance being substantially all iron except the usual impurities in common amounts.

2. An alloy steel consisting of about 1.3% carbon, about 1.5% silicon, about 2% manganese, about 1% molybdenum, about 1.3% copper, and a small amount of beryllium less than .1%, said alloy steel being characterized by the fact that it can be hardened from a temperature of about 1450 F. to a Brinell value or at least 600 and a Rockwell Cone value of at least 60 in both the as cast and the as forged condition.

3. A chromium-free air-hardening tool and die steel consisting of about .05-2.50% of carbon, about fill-2.50% of silicon, about .75-3.25% of manganese, about .25-2.50% of molybdenum, about .35-2.00% of copper, and about .03-.30% of beryllium, with the balance substantially all iron except for the usual impurities in normal amounts.

4. A chromium and tungsten-free air-harden- 0 ing tool and die steel consisting of about .05-2.50% of carbon, about .502.50% of silicon, about .753.25% of manganese, about .25-2.50% of molybdenum, about .35-2.00% of copper, and about .03-.30% of beryllium, with the' balance substantially all iron except for the usual impurities in normal amounts, said steel being characterized by the fact that forgings and castings can be produced therefrom in which the graphite content can be readily controlled.

5. An article of manufacture composed of an alloy steel having the composition defined by claim 3 and containing graphite, the graphite content being substantially uniformly distributed throughout said article in the form of well-defined nodules.

6. An alloy steel capable of being hardened Table V Yield Tensile Elon Bed. r C Si Mn Mo Cu Be State Brinell point, strength. percer it area,

. p. s. 1. p. s. i. in 2" percent 424-A 27 1. 1. 00 1. 00 1. 10 Agata; 11:50" F. 011-111BWH. 95,) 102, 5(1) 8. 0 11. 2

- a 424-A. 27 1. 50 1. 00 1. 00 1. 00 10 AS cast 1,411) F. K 11!. 011 444 68, 000 219, (XX) 4. 5 7. 8 425-A 29 1. 00 1. 50 1. 00 1. (I) 10 AS 0851; 1,411) F. K 12!. 011 415 116, (X1) 216, 5(1) 3. 0 4. 4 425-A 29 1. (I) 1. 50 1. 00 1. 00 10 AS67825}; 1 750 F. Oil-drawn. 100, 000 226, 000 3. 5 10. 3

. a 426-11..-- 27 75 1. 50 1. 00 1. (X) 10 AF 0885 1,750 F. Oil-drawn. 72, 700 196, 950 2. 0 4. 4

1,315 F. air.

The foregoing is illustrative and not limitative and various additions, omissions, substitutions and modifications may be made therein without departing from the'spirit and scope of our invention as defined by the appended claims.

to at least about 600 Brinell and Cone Rockwell from a temperature of from about 1450 F. to 1550 F., and which in addition to iron and the usual impurities consists of from about 1.00% to about 1.50% carbon, from about 35% to about mum 2.50% silicon, from about 115% to about 3.25% manganese, from about 30% to about 2.50% molybdenum, from about 35% to about 2.00% copper and from about .03% to about 30% beryllium.

7. An alloy steel which inaddition to iron and the usual impurities in common amounts consists of from about 1.50% to about 2.25% carbon.

from about 1.00% to about 2.50% silicon, from about 1.50% to about 3.25% manganese, from about 1.50% to about 2.50% molybdenum, from about 1.20% to about 1.50% copper and from uniform distribution oi araphite comprising from about 1.00% to about 1.50% carbon, from about 1.50% to about 2.50% silicon, irom about 1.50% to abo.ut.3.25% manganese, from about 0.25%

to about 2.50% molybdenum, from about 1.25%.

to about 2.00% copper and from about 0.03% to about 0.3% beryllium, with the remainder substantially all iron.

10. A chromium-tree, air-hardening tool and die steel containing from about 0.27% to about 2.50% carbon, from about 0.75% to about 2.50% silicon, from about 1.25% to about 8.25% man- Ianese, from about 0.75% to about 2.25% molybdenum, from about 0.80% to about 2.00% copper and from about 0.03% to about 0.30% beryllium,

with the remainder substantially all iron characteriaed by the fact that it can be hardened to a value of at least 600 Brinell from temperatures 01 from about 1480" l". to about 1550 F.

ENRIQUE G,TOUCEDA. RALPH P. DE VRZIES. 

